Layered composition and processes for preparing and using the composition

ABSTRACT

A layered composition which can be used in various processes has been developed. The composition comprises an inner core such as a cordierite core and an outer layer comprising a refractory inorganic oxide, a fibrous component and an inorganic binder. The refractory inorganic oxide layer can be alumina, zirconia, titania, etc. while the fibrous component can be titania fibers, silica fibers, carbon fibers, etc. The inorganic oxide binder can be alumina, silica, zirconia, etc. The layer can also contain catalytic metals such as gold and platinum plus other modifiers. The layered composition is prepared by coating the inner core with a slurry comprising the refractory inorganic oxide, fibrous component, an inorganic binder precursor and an organic binding agent such as polyvinyl alcohol. The composition can be used in various hydrocarbon conversion processes.

FIELD OF THE INVENTION

This invention relates to a layered composition, a process for preparingand a hydrocarbon conversion process using the composition. Thecomposition comprises an inner core such as cordierite and an outerlayer comprising an outer refractory inorganic oxide and a fibrouscomponent. The outer layer can optionally comprise a catalytic componentdispersed thereon.

BACKGROUND OF THE INVENTION

Numerous commercial processes are carried out using a catalyst. This isespecially true of various hydrocarbon conversion processes. Thesecatalysts comprise one or more catalytic element deposited onto arelatively high surface area support. Further, the catalytic element orcomponent can be evenly dispersed throughout the support, be dispersedon the surface of the support or present as a band below the surface.

The art also discloses catalysts containing an inert core or layer andan active outer layer or shell. For example, U.S. Pat. No. 3,145,183discloses spheres having an impervious center and a porous shell.Although it is disclosed that the impervious center can be small, theoverall diameter is ⅛″ or larger. It is stated that for smaller diameterspheres (less than ⅛″), uniformity is hard to control. U.S. Pat. No.5,516,740 discloses a thin outer shell of catalytic material bonded toan inner core of catalytically inert material. The outer layer can havecatalytic metals such as platinum dispersed on it. The '740 patentfurther discloses that this catalyst is used in an isomerizationprocess. Finally, the outer layer material contains the catalytic metalprior to it being coated onto the inner core.

U.S. Pat. No. 4,077,912 and U.S. Pat. No. 4,255,253 disclose a catalysthaving a base support having deposited thereon a layer of a catalyticmetal oxide or a combination of a catalytic metal oxide and an oxidesupport. U.S. Pat. No. 5,935,889 discloses a catalyst which comprises acatalytically inert core material on which is deposited and bonded athin shell of material containing active sites. Finally, U.S. Pat. No.6,177,381 discloses a layered catalyst composition containing an innercore, an outer layer bonded to the inner core and where the outer layerhas dispersed thereon a platinum group metal, a promoter metal and amodifier metal.

One problem associated with the layered compositions of the prior art isthat the strength or attrition resistance was not sufficient for certainapplications. Applicants have discovered that adding a fibrous componentto the outer layer greatly increases its strength. The fibrouscomponents can be either inorganic fibers such as silica or mullitefibers or organic fibers such as carbon fibers.

SUMMARY OF THE INVENTION

One embodiment of the invention is a layered composition comprising aninner core and an outer layer comprising a refractory inorganic oxideand a fibrous component.

Another embodiment of the invention is a process for preparing thelayered composition described above, the process comprising coating aninner core with a slurry comprising the outer refractory inorganicoxide, a fibrous component, an inorganic binder, an organic bondingagent and a solvent to give a coated core; and calcining the coated coreat a temperature of at least 200° C. for a time sufficient to bond theouter layer to the inner core and provide a layered composition.

Yet another embodiment of the invention is a hydrocarbon conversionprocess comprising contacting a hydrocarbon with the layered compositiondescribed above at conversion conditions to give a converted product.

These and other objects and embodiments will become clearer after adetailed description of the invention.

DETAILED DESCRIPTION OF THE INVENTION

One element of the layered composition of the present invention is aninner core. One characteristic of the materials which can be used forthe inner core is the ability to be formed into a desired shape.Examples of materials which can be used include but are not limited tometals, refractory inorganic oxides and silicon carbide. Refractoryinorganic oxides are preferred with non-limiting examples beingaluminas, cordierite, mullite, montmorillonite, silica, zirconia,titania and mixtures thereof Aluminas include gamma, theta, delta andalpha alumina. A preferred inorganic oxide is cordierite. When the innercore is a refractory inorganic oxide, it is necessary that it bedifferent from the outer layer refractory inorganic oxide.

Further, when the outer layer will have additional components, e.g.metals or metal oxides, which are deposited thereon by impregnationmeans, it is preferred that the inner core have a lower adsorptivecapacity relative to the outer layer. This adsorptive capacity is withrespect to solvents which may be used to impregnate the outer layer witha compound of a catalytic component. The inner core should also have asubstantially lower capacity for the compounds themselves versus theouter layer.

These materials which form the inner core can be formed into a varietyof shapes such as pellets, extrudates, spheres, hollow tubes orirregularly shaped particles although not all materials can be formedinto each shape. Preparation of the inner core can be done by meansknown in the art such as oil dropping, pressure molding, metal forming,pelletizing, granulation, extrusion, rolling methods and marumerizing. Aspherical inner core is preferred. The inner core whether spherical ornot has an effective average diameter of about 0.05 mm to about 15 mmand preferably from about 0.5 mm to about 10 mm. For a non-sphericalinner core, effective diameter is defined as the diameter the shapedarticle would have if it were molded into a sphere. Once the shapedinner core is formed it is optionally calcined at a temperature of about400° C. to about 1500° C.

The inner core is now coated with a layer of a refractory inorganicoxide which is different from the inorganic oxide which may be used asthe inner core and will be referred to as the outer refractory inorganicoxide. This outer refractory oxide is one which has good porosity, has asurface area of at least 2 m²/g, and preferably at least 20 m²/g andmost preferably at least 30 m²/g, an apparent bulk density of about 0.2g/ml to about 1.8 g/ml. Non-limiting examples of the refractoryinorganic oxides which can be used are gamma alumina, delta alumina, etaalumina, theta alumina, silica/alumina, zeolites, non-zeolitic molecularsieves (NZMS), titania, zirconia and mixtures thereof. It should bepointed out that silica/alumina is not a physical mixture of silica andalumina but means an acidic and amorphous material that has beencogelled or coprecipitated. This term is well known in the art, seee.g., U.S. Pat. No. 3,909,450, U.S. Pat. No. 3,274,124 and U.S. Pat. No.4,988,659, all of which are incorporated by reference. Examples ofzeolites include, but are not limited to, zeolite Y, zeolite X, zeoliteL, zeolite beta, ferrierite, MFI, UZM-4(see U.S. Pat. No. 6,776,975),UFI, UZM-8(U.S. Pat. No. 6,756,030), UZM-9(U.S. Pat. No. 6,713,041),mordenite and erionite. Non-zeolitic molecular sieves (NZMS) are thosemolecular sieves which contain elements other than aluminum and siliconand include silicoaluminophosphates (SAPOs) described in U.S. Pat. No.4,440,871, ELAPOs described in U.S. Pat. No. 4,793,984, MeAPOs describedin U.S. Pat. No. 4,567,029 all of which are incorporated by reference.Preferred refractory inorganic oxides are gamma, eta alumina andzirconia.

The refractory inorganic oxide is applied to the inner core by firstforming a slurry comprising the refractory inorganic oxide. The slurryis formed by admixing a solvent with the refractory inorganic oxide toform a mixture and milling the mixture for a time sufficient to form aslurry. The solvent which is usually used is water although organicsolvents can also be used. The mixture can also contain an agent whichwill aid in forming the slurry such as but not limited to nitric acid,hydrochloric acid, sulfuric acid and acetic acid. The slurry will alsocontain an inorganic binder precursor which is usually, a sol, a gel ora compound of a metal which on heating will decompose to form aninorganic oxide binder. The inorganic binders which can be used includebut are not limited to alumina, silica, zirconia, titania, aluminumphosphate, etc. Nonlimiting examples of binder precursors which can beadded to the slurry are: ZrO(C₂H₃O₂)₂; ZrO(NO₃)₂; ZrO (OH)Cl.nH₂O;zirconia sol; ZrOCO₃; ZrO (OH)₂; Zr (C₅H₈O₂)₄; Zr(SO₄)₂.4H₂O; aluminasol; silica sol; aluminum nitrate and boehmite. Although in some casesit is preferred that the binder give the same refractory oxide as theouter layer oxide, generally any inorganic binder can be used with anyouter layer refractory oxide. For example, an alumina binder can be usedwhen the outer layer is a zeolite, titania, silica or alumina. However,it has been found that when zirconia is the outer refractory inorganiclayer, it is preferred to have a zirconia binder. The amount ofinorganic binder precursor present in the slurry is that amount whichwill provide from about 1 wt. % to about 99 wt. % inorganic binder onthe deposited outer layer. Preferably the amount of binder precursorpresent is that amount which will give from 2 to 40 wt. % of the outerlayer of inorganic binder and most preferably the amount which willprovide from 5 to 30 wt. % of the outer layer.

Another necessary component of the slurry is a fibrous component.Suitable fibrous components include those that comprise fibers that areelongated, thread-like objects or structures or filaments. The types offibers which can be used include both inorganic and organic fiberseither of which can be natural or synthetic. Generally fibers cancomprise a large array of materials including without limitationglasses, minerals, metal oxides, ceramics, metals, polymers and carbons.Specific examples of inorganic fibers include but are not limited totitania fibers, potassium titanate fibers, zirconia fibers, mullitefibers, alumina fibers, silicon carbide fibers, glass wool, boronfibers, aluminum fibers, silica fibers and cordierite fibers. Apreferred fiber which is mostly silica (60% SiO₂, 33% CaO and 6% MgO) isSuperwool™ manufactured and sold by Thermal Ceramics. Nonlimitingexamples of organic fibers are graphite fibers, carbon fibers andpolymeric fibers such as polyethylenes, polyesters, polyurethanes,polyamides, aromatic polyamides (e.g. Kevlar™), polystyrenes (e.g.syndiotactic polystyrene), polytetrafluoroethylenes (e.g. Teflon™).Furthermore, combinations of materials may be used in the fibers as wellas combinations of fibers in the fibrous component. It should be pointedout that when organic fibers are used, the subsequent treatingtemperatures and the process temperature that it will be used at must bebelow the combustion temperature of the organic fibers. Obviously theinorganic fibers will not combust, but the operating temperature must bebelow its melting temperature. Furthermore, fibers may be furthertreated (e.g. coated) to accentuate desirable characteristics (e.g.treated to increase decomposition or melting temperature). While thefibrous component may include fibers that are woven, braided orotherwise entangled or connected in an unwoven manner, the fibers mayalso be free of connections with other fibers.

Although the length of the fibers is not critical, usually the fibershave a length from about 1 to about 10,000 micrometers, preferably fromabout 2 to about 1,000 micrometers and most preferably from about 5 toabout 300 micrometers. The fibers also have varying diameters whichagain is not critical. Smaller diameter fibers are more easily dispersedand thus are preferred. Since both the length and diameter of the fiberscan be varied, a preferred length/diameter (L/D) ratio can be determinedexperimentally. This L/D ratio is different for different fibers.

The amount of fibers which can be added to the slurry can varyconsiderably and is usually that amount which will give from about 1 toabout 30 wt. % of the final layer weight, preferably from about 1 toabout 20 wt. % and most preferably from about 3 to about 10 wt. %.

It is also necessary that the slurry contain an organic bonding agentwhich aids in the adhesion of the layer material to the inner core.Examples of this organic bonding agent include but are not limited topolyvinyl alcohol (PVA), hydroxy propyl cellulose, methylcellulose andcarboxy methylcellulose. The amount of organic bonding agent which isadded to the slurry will vary considerably from about 0.1 wt. % to about5 wt. % of the slurry.

As stated, the slurry is milled using any of a variety of mills known inthe art such as ball milling, impact milling, etc. Milling is carriedout to ensure adequate blending of the various components and tooptionally reduce the particle size of the refractory inorganic oxidepowder and/or fibers. Milling is usually carried out for a time of about2 to about 8 hours.

Coating of the inner core with the slurry can be accomplished by meanssuch as rolling, dipping, spraying, etc. One preferred techniqueinvolves using a fixed fluidized bed of inner core particles andspraying the slurry into the bed to coat the particles evenly. Thethickness of the layer can vary considerably, but usually is from about40 to about 400 micrometers preferably from about 40 to about 300micrometers and most preferably from about 50 to about 200 micrometers.It should be pointed out that the optimum layer thickness depends on theuse for the catalyst and the choice of the outer refractory oxide. Oncethe inner core is coated with the layer of outer refractory inorganicoxide, the resultant layered composition is dried at a temperature ofabout 100° C. to about 150° C. for a time of about 1 to about 24 hoursand then calcined at a temperature of at least 200° C. for a time ofabout 0.5 to about 10 hours to effectively bond the outer layer to theinner core and provide a layered composition. The calcination conditionsare chosen to not only effectively bond the outer layer to the innercore but to optimize the characteristics of the outer layer, e.g.surface area of the layer, integrity of the fibers, pore volume of theinorganic oxide etc. As stated above, if organic fibers are used thecalcination temperature must be below their combustion temperature.Thus, preferred calcination temperatures are from about 200° C. to about1500° C. and most preferably from about 400° C. to about 1100° C.Finally, the drying and calcining steps can be combined into one step.It should also be pointed out that in some cases it may be necessary tocarry out the layering process more than once in order to obtain thedesired layer thickness. Intermediate calcining steps may not benecessary with a drying step being sufficient to ensure that the firstlayer does not dissolve during the subsequent layering step.

In one embodiment of the invention, the layered composition comprisesmore than one layer. Successive layers are applied to the coatedcomposition after the first (or subsequent layer) has been calcined.Coating of a layered core is carried out as described above for thefirst layer. The second layer of refractory inorganic oxide is differentfrom the first layer and will be different from the third layer (ifany), although the first and third layer can be the same inorganicoxide. Thus, it is only necessary that adjacent layers be of differentrefractory inorganic oxides. The thickness of each layer is as statedfor the first layer and the number of additional layers can vary from 1to about 5 layers or more.

As stated the use of fibers in the outer layer greatly improves thestrength or attrition resistance of the resultant layered composition.The strength of the layered composition was determined by measuring itsimpact breakage (IB). Impact breakage was determined by taking an amountof layered composition (about 50 cc) after calcination, placing them ina flat drum and rotating the drum at 25 rpm for 10 minutes. The fineswere collected, weighted and the IB determined from the followingequation:IB=(Weight of Fines/Total Weight of Layered Composition)×100%

The layered composition of the invention will have an IB of preferablyless than about 10 wt. %, more preferably less than about 5 wt. % andmost preferably less than about 3 wt. %. Ranges within the above statedranges are also contemplated.

Although the layered composition described above can be used as is tocatalyze various reactions, it is usually used as a support for variouscatalytic components. These catalytic components are selected from thegroup consisting of Groups 3-12 of the Periodic Table of the Elementsusing the IUPAC system of numbering the groups and as set forth athttp://pearl1.lanl.gov/periodic/default.htm. Preferred catalyticelements or metals are the noble metals or platinum group metals whichinclude platinum, palladium, rhodium, ruthenium, osmium and iridium.Gold and silver are also preferred catalytic metals. Combinations ofcatalytic components are also preferred, such as palladium used incombination with gold and/or rhodium.

These catalytic metal components can be deposited on the layered supportin any suitable manner known in the art. One method involvesimpregnating the layered composition or support with a solution (usuallyaqueous, although organic solvents can be used) of a decomposablecompound of the catalytic metal or metals. By decomposable is meant thatupon heating the metal compound is converted to the metal or metal oxidewith the release of byproducts. Examples of the compounds which can beused include without limitation chlorides, other halides, nitrates,nitrites, hydroxides, oxides, oxalates, acetates, sulfates and amines.Illustrative examples of decomposable compounds of the platinum groupmetals are chloroplatinic acid, ammonium chloroplatinate, bromoplatinicacid, dinitrodiamino platinum, sodium tetranitroplatinate, rhodiumtrichoride, hexa-amminerhodium chloride, rhodium carbonylchloride,sodium hexanitrorhodate, chloropalladic acid, palladium chloride,palladium nitrate, diamminepalladium hydroxide, tetraamminepalladiumchloride, hexachloroiridate (IV) acid, hexachloroiridate (III) acid,ammonium hexachloroiridate (III), ammonium aquohexachloroiridate (IV),ruthenium tetrachloride, hexachlororuthenate, hexa-amminerutheniumchloride, osmium trichloride and ammonium osmium chloride. Examples ofother palladium compounds include but are not limited to Na₂PdCl₄,Pd(NH₃)₄(NO₂)₂, Pd(NH₃)₄(OH)₂, Pd(NH₃)₄(NO₃)₂, Pd(NH₃)₄(OAc)₂,Pd(NH₃)₂(OAc)₂, Pd(OAc)₂ in KOH and/or NMe₄OH and/or NaOH,Pd(NH₃)₄(HCO₃)₂ and palladium oxalate. Examples of gold and silvercompounds include but are not limited to AuCl₃, HAuCl₄, NaAuCl₄, KAuO₂,NaAuO₂, NMe₄AuO₂, Au(OAc)₃, HAu(NO₃)₄, AgNO₃, AgC₂H₃O₂ and AgClO₃.Solubility modifiers may be utilized to aid in solubilizing thedecomposable compound of the catalytic metal or metals. For example,acids or bases may be used to facilitate the catalytic compound goinginto solution. In one embodiment, KOH and/or NMe₄OH is used incombination with Au(OAc)₃ or nitric acid is used with HAu(NO₃)₄.

Multiple solutions containing the catalytic compounds may be impregnatedonto the layered composition or support simultaneously (e.g.co-impregnation) or sequentially and may be impregnated through the useof one or multiple solutions.

One or more calcining steps may be used, such that at any point after atleast one catalytic component compound is contacted with the layeredcomposition or refractory inorganic oxide, it may be calcined. Forexample, the calcining step is carried out at a temperature in the rangeof about 100° C. to about 700° C., preferably between about 200° C. andabout 500° C. in a non-reducing atmosphere. Calcination times may varybut preferably are between about 1 and 5 hours. The degree ofdecomposition of the catalytic component compound depends on thetemperature used and length of time the impregnated catalyst is calcinedand can be followed by monitoring volatile decomposition products.

Preferably, the last calcining step occurs before contact of the goldcatalytic component to a zirconia containing layered composition.Alternately, calcining of a zirconia containing support compositioncontaining gold is conducted at temperatures below about 300° C.Exemplary protocols including a calcining step include: a) impregnatingwith palladium followed by calcining followed by impregnating with gold;b) co-impregnating palladium and rhodium followed by calcining followedby impregnating with gold; c) impregnating with palladium followed bycalcining followed by impregnating with rhodium followed by calciningfollowed by impregnating with gold; or d) impregnating with palladiumand rhodium, followed by impregnating with gold, followed bycalcination.

One impregnation procedure involves the use of a steam-jacketed rotarydryer. The layered composition is immersed in the impregnating solutioncontaining the desired metal compound(s) contained in the dryer and thesupport is tumbled therein by the rotating motion of the dryer.Evaporation of the solution in contact with the tumbling support isexpedited by applying steam to the dryer jacket. The resultant compositeis allowed to dry under ambient temperature conditions, or dried at atemperature of about 80° to about 110° C., followed by calcination,thereby converting the metal compound to the metal or metal oxide.

Another impregnation procedure is spray impregnation which is well knownin the art and is presented here only for completeness. The layeredcomposition is loaded into a drum and a spray nozzle is inserted intothe opening of the drum. The support is tumbled and the metal containingsolution is delivered through the spray nozzle for 15 to 30 minutes. Theamount of solution can be varied to determine the depth of penetrationinto the support. The support is dried at 110° C. to 150° C. andadditional metals can be added by repeating the above procedure or thesupport can be calcined to convert the metal compounds to the metal ormetal oxide.

The dispersion of the catalytic metals can either be done as describedabove after the refractory inorganic oxide has been applied to the innercore or the refractory inorganic oxide can first be impregnated with thedesired solution, dried, calcined, slurried and then applied to theinner core. If the layered composition contains more than one layer, allthe layers need not have catalytic metals dispersed thereon. Forexample, the first layer can have one or more catalytic metal dispersedthereon, while the second layer does not have any catalytic metalsthereon or vice versa. Alternatively, the first layer can have one ormore catalytic metal while the second layer has different catalyticmetal(s).

In addition to the catalytic components, various promoters and modifierscan also be dispersed on the layered composition. Promoters andmodifiers can be any elements selected from the group consisting ofalkali metals, alkaline earth metals, tin, germanium, rhenium, gallium,bismuth, lead, indium, cerium, zinc, boron and mixtures thereof. Onepreferred promoter for use in vinyl acetate production is an alkalimetal, which may be provided in the form of an acetate such as KOAc. Theaddition of the alkali metal may be referred to as activating thecatalyst.

The promoter and modifier components can be dispersed onto the layeredsupport in the same way as described for the catalytic component. Allthe components can be impregnated using one common solution or they canbe sequentially impregnated in any order, but not necessarily withequivalent results. Additionally, these promoters and modifiers can bepresent in one layer, but not in another layer. They can also be presentin a layer where there are no catalytic metals or only in layers wherethere are catalytic metals.

When it is stated that the catalytic components, promoters and modifiersare “dispersed or deposited on” the outer layer it is meant that theycan be dispersed either on the surface of the layer, throughout thelayer or even below the outer surface in a tight band. It should bepointed out that when the inner core comprises a material that has someadsorptive property, a small fraction of the catalytic component,promoter and/or modifier can be found on or throughout the core.

The catalysts of the present invention may be utilized to producealkenyl alkanoates from an alkene, alkanoic acid and an oxygencontaining gas in the presence of a catalyst. Preferred alkene startingmaterials contain from two to four carbon atoms (e.g. ethylene,propylene and n-butene). Preferred alkanoic acid starting materials usedin the process of this invention for producing alkenyl alkanoatescontain from two to four carbon atoms (e.g., acetic, propionic andbutyric acid). Preferred products of the process are vinyl acetate,vinyl propionate, vinyl butyrate, and allyl acetate. The most preferredstarting materials are ethylene and acetic acid with the vinyl acetatebeing the most preferred product. Thus, the present invention is usefulin the production of olefinically unsaturated carboxylic esters from anolefinically unsaturated compound, a carboxylic acid and oxygen in thepresence of a catalyst. Other methods of making alkenyl alkanoates maybe found in U.S. application Ser. No. 10/993,507, which incorporated byreference.

When vinyl acetate is produced using the catalyst of the presentinvention, a stream of gas, which contains ethylene, oxygen or air, andacetic acid is passed over the catalyst. The composition of the gasstream can be varied within wide limits, taking into account the zone offlammability of the effluent. For example, the molar ratio of ethyleneto oxygen can be about 80:20 to about 98:2, the molar ratio of aceticacid to ethylene can be about 100:1 to about 1:100, preferably about10:1 to 1:10, and most preferably about 1:1 to about 1:8. The gas streammay also contain gaseous alkali metal acetate and/or inert gases, suchas nitrogen, carbon dioxide and/or saturated hydrocarbons. Reactiontemperatures which can be used are elevated temperatures, preferablythose in the range of about 125-220° C. The pressure employed can be asomewhat reduced pressure, normal pressure or elevated pressure,preferably a pressure of up to about 2026 kPa (20 atmospheres gauge).

For a vinyl acetate catalyst according to the present inventionpreferably comprises between about 1 to about 10 grams of palladium, andabout 0.5 to about 10 grams of gold per liter of catalyst. The amount ofgold is preferably from about 10 to about 125 wt % based on the weightof palladium. Further, the catalyst preferably contains about 10 toabout 70, preferably about 20 to about 60 grams of promoter (e.g. KOAc)per liter of catalyst.

In one application, a layered catalytic composite is used to producevinyl acetate from the reaction of ethylene with acetic acid and oxygen.In this particular case, the inner core preferably comprises cordieriteand the refractory oxide layer is a zirconia layer having fibers such asmullite, Superwool or TiO₂. The layered composition has dispersedthereon palladium, gold and potassium with rhodium being optional. Apreferred method of dispersing the metals onto the support is to firstimpregnate the layered support with an aqueous solution comprising apalladium compound such as Pd(NH₃)₄ (OH)₂ and then calcining theimpregnated layered composition. Next the calcined composition isimpregnated with a solution comprising a gold compound such as KAuO₂,drying, calcining, and finally reducing the catalyst at a temperaturefrom ambient to about 550° C. for a time of about 1 to about 5 hours.Reduction is carried out under hydrogen or other reducing atmospheres.Addition of a promoter may be carried out before or after the reductionstep.

The layered composition of the invention with catalytic metals thereoncan also be used for other hydrocarbon conversion processes such ashydrocracking, cracking, isomerization, hydrogenation, dehydrogenation,oxidation and alkylation of both aromatic and isoparaffin hydrocarbons.The desirable catalytic metals for these reactions are the platinumgroup metals, as described above. Promoter metals selected from thegroup consisting of Sn, Ge, Re, Ga, Bi, Pb, In, Ce, Zn and mixturesthereof can also be present as well as modifier metals selected from thegroup consisting of alkali metals, alkaline earth metals and mixturesthereof can also de dispersed on the layered support. Methods ofdispersing these various components onto the layered support are as setforth above. As described in U.S. Pat. No. 6,280,608 B1 and incorporatedherein by reference in its entirety, a halogen component can also bepresent on the layered catalytic component.

Although in the above embodiments all three metals are uniformlydispersed in the outer layer of refractory oxide and substantiallypresent only in the outer layer, it is also within the bounds of thisinvention that the modifier metal can be present both in the outer layerand the inner core. This is owing to the fact that the modifier metalcan migrate to the inner core, when the core is other than a metalliccore.

Although the concentration of each metal component can varysubstantially, it is desirable that the platinum group metal be presentin a concentration of about 0.01 to about 5 weight percent on anelemental basis of the entire weight of the catalytic composition andpreferably from about 0.05 to about 2.0 wt. %. The promoter metal ispresent in an amount from about 0.05 to about 10 wt. % of the entirecatalytic composition while the modifier metal is present in an amountfrom about 0.1 to about 5 wt. % and preferably from about 2 to about 4wt. % of the entire catalytic composition.

The conditions necessary to carry out alkylation of aromatic compoundsare well known and are disclosed, for example, in U.S. Pat. No.3,965,043 and U.S. Pat. No. 3,979,331 which are incorporated byreference. Generally the process can be carried out in a batch type or acontinuous type operation. In a batch type process, the catalyst,aromatic compound and alkylating agent are placed in an autoclave andthe pressure increased, if necessary, in order to effect the reaction inthe liquid phase. An excess amount of aromatic compound should bepresent, preferably in a range of about 2:1 to about 20:1 moles ofaromatic compound per mole of alkylating agent. The reaction is carriedout at an elevated temperature since the rate of alkylation isundesirably low at room temperature. Preferably the temperature is inthe range of about 40° C. to about 200° C. The process is carried outfor a time of about 0.5 to about 4 hours, after which the product isseparated from the starting materials by conventional means.

If it is desired to carry out the process in a continuous manner, thecatalyst is placed in a reactor which is heated to the desired operatingtemperature and the pressure increased above atmospheric, if necessary.The aromatic compound and alkylating agent are flowed over the catalystbed at a predetermined liquid hourly space velocity sufficient to effectalkylation. The effluent is continuously withdrawn and conventionalseparation means used to isolate the desired product.

Hydrocracking conditions typically include a temperature in the range of240° C. to 649° C. (400° F.-1200° F.), preferably between about 316° C.and about 510° C. (600-950° F.). Reaction pressures are in the range ofatmospheric to about 24,132 kpag (3,500 psig), preferably between about1,379 and 20,685 kPag (200-3,000 psig). Contact times usually correspondto liquid hourly space velocities (LHSV) in the range of about 0.1 hr⁻¹to 15 hr⁻¹, preferably between about 0.2 and 3 hr⁻¹. Hydrogencirculation rates are in the range of about 178 to 8,888 standard cubicmeters per cubic meter of charge (1,000 to 50,000 standard cubic feet(scf) per barrel of charge) preferably between about 355 to about 5,333std. m³/m³ (2,000 and 30,000 scf per barrel of charge).

The reaction zone effluent is normally removed from the catalyst bed,subjected to partial condensation and vapor-liquid separation and thenfractionated to recover the various components thereof. The hydrogenand, if desired some or all of the unconverted heavier materials, arerecycled to the reactor. Alternatively, a two-stage flow may be employedwith the unconverted material being passed into a second reactor.Catalysts of the subject invention may be used in just one stage of sucha process or may be used in both reactor stages.

Catalytic cracking processes are preferably carried out with thecatalyst composition using feedstocks such as gas oils, heavy naphthas,deasphalted crude oil residua, etc. with gasoline being the principaldesired product. Temperature conditions of about 454° C. to about 593°C. (850° to 1100° F.,) LHSV values of 0.5 to 10 hr⁻¹ and pressureconditions of from about 0 to about 345 kpag (50 psig) are suitable.

Isomerization reactions are carried out in a temperature range of about371° C. to about 538° C. (700-1000° F.). Olefins are preferablyisomerized at temperatures of about 260° C. to about 482° C. (500° F. to900° F.), while paraffins, naphthenes and alkyl aromatics are isomerizedat temperatures of about 371° C. to 538° C. (700° F. to 1000° F.).Hydrogen pressures are in the range of about 689 to about 3,445 kPag(100 to 500 psig). Contact times usually correspond to liquid hourlyspace velocities (LHSV) in the range of about 0.1 hr⁻¹ to 10 hr⁻¹.Hydrogen to hydrocarbon molar ratios in the range of 1 to 20, preferablybetween 4 and 12.

In a dehydrogenation process, dehydrogenatable hydrocarbons arecontacted with the catalyst of the instant invention in adehydrogenation zone maintained at dehydrogenation conditions. Thiscontacting can be accomplished in a fixed catalyst bed system, a movingcatalyst bed system, a fluidized bed system, etc., or in a batch-typeoperation. A fixed bed system is preferred. In this fixed bed system thehydrocarbon feed stream is preheated to the desired reaction temperatureand then flowed into the dehydrogenation zone containing a fixed bed ofthe catalyst. The dehydrogenation zone may itself comprise one or moreseparate reaction zones with heating means there between to ensure thatthe desired reaction temperature can be maintained at the entrance toeach reaction zone. The hydrocarbon may be contacted with the catalystbed in either upward, downward or radial flow fashion. Radial flow ofthe hydrocarbon through the catalyst bed is preferred. The hydrocarbonmay be in the liquid phase, a mixed vapor-liquid phase or the vaporphase when it contacts the catalyst. Preferably, it is in the vaporphase.

Hydrocarbons which can be dehydrogenated include hydrocarbons with 2 to30 or more carbon atoms including paraffins, isoparaffins,alkylaromatics, naphthenes and olefins. A preferred group ofhydrocarbons is the group of normal paraffins with 2 to about 30 carbonatoms. Especially preferred normal paraffins are those having 2 to 15carbon atoms.

Dehydrogenation conditions include a temperature of from about 400° C.to about 900° C., a pressure of from about 1 to about 1013 kPa and aliquid hourly space velocity (LHSV) of from about 0.1 to about 100 hr⁻¹.Generally for normal paraffins the lower the molecular weight the higherthe temperature required for comparable conversion. The pressure in thedehydrogenation zone is maintained as low as practicable, consistentwith equipment limitations, to maximize the chemical equilibriumadvantages.

The effluent stream from the dehydrogenation zone generally will containunconverted dehydrogenatable hydrocarbons, hydrogen and the products ofdehydrogenation reactions. This effluent stream is typically cooled andpassed to a hydrogen separation zone to separate a hydrogen-rich vaporphase from a hydrocarbon-rich liquid phase. Generally, thehydrocarbon-rich liquid phase is further separated by means of either asuitable selective adsorbent, a selective solvent, a selective reactionor reactions or by means of a suitable fractionation scheme. Unconverteddehydrogenatable hydrocarbons are recovered and may be recycled to thedehydrogenation zone. Products of the dehydrogenation reactions arerecovered as final products or as intermediate products in thepreparation of other compounds.

The dehydrogenatable hydrocarbons may be admixed with a diluent materialbefore, while or after being flowed to the dehydrogenation zone. Thediluent material may be hydrogen, steam, methane, ethane, carbondioxide, nitrogen, argon and the like or a mixture thereof Hydrogen isthe preferred diluent. Ordinarily, when hydrogen is utilized as thediluent it is utilized in amounts sufficient to ensure a hydrogen tohydrocarbon mole ratio of about 0.1:1 to about 40:1, with best resultsbeing obtained when the mole ratio range is about 1:1 to about 10:1. Thediluent hydrogen stream passed to the dehydrogenation zone willtypically be recycled hydrogen separated from the effluent from thedehydrogenation zone in the hydrogen separation zone.

Water or a material which decomposes at dehydrogenation conditions toform water such as an alcohol, aldehyde, ether or ketone, for example,may be added to the dehydrogenation zone, either continuously orintermittently, in an amount to provide, calculated on the basis ofequivalent water, about 1 to about 20,000 weight ppm of the hydrocarbonfeed stream. About 1 to about 10,000 weight ppm or water addition givesbest results when dehydrogenating paraffins having from 2 to 30 or morecarbon atoms.

Hydrogenation processes including selective hydrogenation of dienes andtrienes can be carried out using reactors and hydrogenation zonessimilar to the dehydrogenation process described above. Specifically,hydrogenation conditions include pressures of about 0 kPag to about13,789 kPag, temperatures of about 30° C. to about 280° C., H₂ tohydrogenatable hydrocarbon mole ratios of about 5:1 to about 0.1:1 andLHSV of about 0.1 to about 20 hr⁻¹.

The layered catalysts of this invention can also be used in oxidationreactions. These oxidation reactions include:

-   -   1) partial oxidation of hydrocarbon streams, such as naphtha or        methane, to generate synthesis gas (CO+H₂);    -   2) selective oxidation of hydrogen produced from endothermic        dehydrogenation reactions such as ethylbenzene to styrene; and,    -   3) oxidation of methane, ethane or carbon monoxide to clean up        flue gas emissions from combustion processes.

The layered sphere catalyst will be of most benefit to processes wherethe activity or selectivity of the catalyst is limited by intraparticlediffusional resistance of product or reactants.

The conditions for the oxidation process depend on the individualprocess application but are generally about 350° C. to about 800° C.,about 40 kPa to about 2030 kPa, with a diluent present in the feedstreamsuch as N₂, CO₂, HO to control the reaction. Hydrogen may also bepresent as a diluent and also a reactant. For the selective oxidation ofhydrogen, the molar ratio of oxygen to H₂ may vary from about 0.05 toabout 0.5. The diluent level is generally from about 0.1 to about 10moles of diluent per mole of hydrocarbon. For example, the steam toethylbenzene molar ratio may be from about 5:1 to about 7:1 during thedehydrogenation of ethylbenzene. Typical space velocity for oxidation isbetween about 0.5 to about 50 hr⁻¹ LHSV.

The following examples are presented in illustration of this inventionand are not intended as undue limitations on the generally broad scopeof the invention as set out in the appended claims.

EXAMPLE 1

A slurry was prepared by adding to a vessel 634.2 g of deionized water,110 g of 15% of poly-vinyl alcohol (PVA) solution and 11.1 g of aceticacid. The subsequent mixture was stirred and to it there were added221.8 g of zirconia powder followed by 272.8 g of zirconia sol binder.The resultant mixture was milled for 8 hours.

This resultant slurry was used to spray 700 g of 7 mm diametercordierite spheres using a coating apparatus to give a layer having anaverage thickness of 200 micrometer. The coated spheres were unloadedfrom the coating chamber and heated in air up to 600° C. where they werecalcined for 4 hours under dry air. The calcined spheres were tested forattrition resistance by taking 50 cc of the calcined spheres, placingthem in a flat drum and rotating the drum at 25 rpm for 10 minutes. Theimpact breakage (IB) was determined as the weight percent finesgenerated versus the total weight of the spheres. The IB for this samplewas found to be 17.5 wt. %.

EXAMPLE 2

Into a container there were added 1,021.6 g of deionized water, 205.9 gof a 15% PVA solution and 21.2 g of acetic acid. The mixture was stirredand to it there were added 27.3 g of mullite fibers comprising 80%Al₂O₃, 20% SiO₂ with an average fiber length of about 200 micrometersand an average diameter of about 3 micrometers. Next, 426.2 g ofzirconia powder was added followed by 469.8 g of zirconia sol binder.The mixture was then ballmilled for about 6 hours.

The resultant slurry from above was sprayed onto 711 g of 7 mm diametercordierite spheres using a slurry coating apparatus to obtain wetspheres having an outer layer of about 200 micrometers thick. The wetspheres were heated in air to 600° C. and calcined at 600° C. for 4hours under dry air. The calcined spheres were tested for impactbreakage and were found to have an IB of 3.3 wt. %.

EXAMPLE 3

A slurry was formed by adding 1,121.7 g of deionized water and 225.5 gof a 15% PVA solution and 23.2 g of acetic acid into a vessel. Theresultant mixture was stirred and to it there were added 29.9 g ofmullite fibers as described in Example 2 followed by the addition of463.9 g of zirconia powder and then 514.5 g of zirconia sol binder. Theresultant slurry was ballmilled for 6 hours.

The resultant slurry was used to deposit a layer onto 800 g of 7 mmdiameter cordierite spheres using a slurry coating apparatus therebyproducing wet spheres having a layer with an average thickness of about100 micrometers. The wet spheres were calcined at 600° C. for 4 hoursunder dry air and were found to have an IB of 3.0 wt. %.

EXAMPLE 4

Into a mixing vessel there were added 602.8 g of deionized water, 122.5g of a 15% PVA solution and 12.6 g of acetic acid. The mixture wasstirred and to it there were added 15.3 g of titania fibers having anaverage length of about 3 micrometers and an average diameter of about0.3 micrometers. Next 253.7 g of zirconia powder were added followed by279.6 g of zirconia sol binder. The resulting slurry was ballmilled for6 hours.

The slurry described above was used to deposit a layer onto 730 g of 7mm diameter cordierite spheres by spraying the slurry onto the spheresusing a slurry coating apparatus to give wet spheres having an outerlayer of with an average thickness of 200 micrometers. The wet sphereswere calcined at 600° C. under dry air for 4 hours. The calcined sphereswere tested and were found to have an IB of 2.0 wt. %.

EXAMPLE 5

Into a mixing vessel there were added 622.1 g of deionized water, 129 gof 15% PVA solution and 13.1 g of acetic acid. The mixture was stirredand to it there were added 35.8 g of titania fibers as described inExample 4 followed by the addition of 263.8 g of zirconia powder andfinally 310.4 g of zirconia sol binder. The resultant slurry wasballmilled for about 6 hours. The slurry contained approximately 10 wt.% titania fibers.

A portion of the slurry was deposited onto 730 g of 7 mm diametercordierite spheres using a slurry coating system to give a layer havingan average thickness of about 200 micrometers. The wet spheres werecalcined at 600° C. for 4 hours under dry air and were found to have anIB of 1.4 wt. %.

It will be further appreciated that functions or structures of aplurality of components or steps may be combined into a single componentor step, or the functions or structures of one-step or component may besplit among plural steps or components. The present inventioncontemplates all of these combinations. Unless stated otherwise,amounts, dimensions and geometries of the various components depictedherein are not intended to be restrictive of the invention, and otheramounts, dimensions or geometries are possible. It will also beappreciated from the above that the fabrication of the unique catalystsherein and the use thereof also constitute methods in accordance withthe present invention. The present invention also encompassesintermediate (e.g. pre-catalysts) and end products resulting from thepractice of the methods herein. The use of “comprising”, “having”,“containing” or “including” also contemplates embodiments that “consistessentially of” or “consist of” the recited feature.

The explanations and examples presented herein are intended to acquaintothers skilled in the art with the invention, its principles, and itspractical application. Those skilled in the art may adapt and apply theinvention in its numerous forms, as may be best suited to therequirements of a particular use. Accordingly, the specific embodimentsof the present invention as set forth are not intended as beingexhaustive or limiting of the invention. The scope of the inventionshould, therefore, be determined not with reference to the abovedescription, but should instead be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled. The disclosures of all articles and references,including patents, patent applications and publications, areincorporated by reference for all purposes.

1. A layered composition comprising an inner core and, an outer layerover the inner core, the outer layer comprising a refractory inorganicoxide, a fibrous component and an inorganic binder.
 2. The compositionof claim 1 where the fibrous component is selected from the groupconsisting of inorganic fibers, organic fibers and mixtures thereof. 3.The composition of claim 2 where the inorganic fibers are selected fromthe group consisting of mullite, titania, potassium titanate, alumina,zirconia, silica, silicon carbide, cordierite, glass and mixturesthereof.
 4. The composition of claim 2 where the organic fibers areselected from the group consisting of graphite, carbon, polymers andmixtures thereof.
 5. The composition of claim 1 where the inner core isselected from the group consisting of alpha alumina, theta alumina,silicon carbide, metals, cordierite, montmorillonite, gamma alumina andmixtures thereof.
 6. The composition of claim 1 where the outerrefractory inorganic oxide is selected from the group consisting ofgamma alumina, delta alumina, eta alumina, theta alumina,silica/alumina, zeolites, nonzeolitic molecular sieves, titania,zirconia, niobia and mixtures thereof.
 7. The composition of claim 1where the inorganic binder is selected from the group consisting ofalumina, silica, zirconia, titania, aluminum phosphate and mixturesthereof.
 8. The composition of claim 1 where the layered composition hasan impact breakage of less than 10 wt. %.
 9. The composition of claim 1further comprising a catalytic component dispersed on the outer layerand selected from the group consisting of an element from Groups 3-12 ofthe Periodic Table of the Elements (IUPAC) and mixtures thereof.
 10. Thecomposition of claim 9 where the catalytic component is selected fromthe group consisting of Pd, Rh, Au, Pt, Ag, Rh, Ir, Os and mixturesthereof.
 11. The composition of claim 9 further comprising a modifiercomponent dispersed on the outer layer and selected from the groupconsisting of alkali metals, alkaline earth metals, tin, germanium,rhenium, gallium, bismuth, lead, indium, cerium, zinc, boron andmixtures thereof.
 12. The composition of claim 9 where the outer layerhas deposited thereon from one to about 5 additional layers and whereadjacent layers comprise different inorganic oxides.
 13. The compositionof claim 1 where the outer layer has deposited thereon from one to about5 additional layers and where adjacent layers comprise differentinorganic oxides.
 14. The composition of claim 13 where at least one ofthe additional layers has a catalytic component dispersed thereon andwhere the catalytic component is selected from the group consisting ofan element from Groups 3-12 of the Periodic Table of the Elements(IUPAC) and mixtures thereof.
 15. A process for preparing a layeredcomposition comprising an inner core, and an outer layer over the innercore, the outer layer comprising a refractory inorganic oxide, a fibrouscomponent and an inorganic binder, the process comprising: coating aninner core with a slurry comprising an outer refractory inorganic oxide,a fibrous component, an inorganic binder precursor, an organic bondingagent and a solvent to give a coated core; and calcining the coated coreat a temperature of at least 200° C. for a time sufficient to bond theouter layer to the inner core and provide a layered composition.
 16. Theprocess of claim 15 where the organic bonding agent is selected from thegroup consisting of polyvinyl alcohol (PVA), hydroxyl propyl cellulose,methyl cellulose, carboxy methylcellulose and mixtures thereof.
 17. Theprocess of claim 15 where the inorganic binder precursor is selectedfrom the group consisting of ZrO (C₂H₃O₂)₂, ZrO (NO₃)₂, zirconia sol,alumina sol, silica sol, aluminum nitrate and mixtures thereof.
 18. Theprocess of claim 15 wherein the refractory inorganic oxide has dispersedthereon a catalytic component selected from the group consisting of anelement from Groups 3-12 of the Periodic Table of the Elements (IUPAC).19. The process of claim 15 further comprising impregnating the layeredcomposition with a solution comprising a catalytic metal compound toprovide an impregnated layered composition and calcining the impregnatedlayered composition at a temperature of about 200° C. to about 700° C.for a time sufficient to provide a catalytic metal component on theouter refractory inorganic oxide layer and where the catalytic metal isselected from the group consisting of an element from Groups 3-12 of thePeriodic Table of the Elements (IUPAC).
 20. The process of claim 19where the solution further comprises a modifier component compound andwhere the modifier component is selected from the group consisting ofalkali metals, alkaline earth metals, tin, germanium, rhenium, gallium,bismuth, lead, indium, cerium, zinc, boron and mixtures thereof.
 21. Theprocess of claim 15 where the coating and calcining steps are repeatedfrom 1 to about 5 times to provide multiple layers.
 22. The process ofclaim 21 where one or more of the layers has dispersed thereon acatalytic component selected from the group consisting of an elementfrom Groups 3-12 of the Periodic Table of the Elements (IUPAC).
 23. Theprocess of claim 15 where the fibrous component is selected from thegroup consisting of inorganic fibers, organic fibers and mixturesthereof.
 24. The process of claim 23 where the inorganic fibers areselected from the group consisting of mullite, titania, potassiumtitanate, alumina, zirconia, silica, silicon carbide, cordierite, glassand mixtures thereof.
 25. The composition of claim 23 where the organicfibers are selected from the group consisting of graphite, carbon,polymers and mixtures thereof.
 26. A hydrocarbon conversion processcomprising contacting a hydrocarbon stream with a layered composition athydrocarbon conversion conditions to give a converted product, thelayered composition comprising an inner core comprising a substantiallynon-porous component and an outer layer comprising a refractoryinorganic oxide and a fibrous component.